Transformer in UPS runs warm for no apparent reason

[evilkitty]

Running temp in open air is 27.5C to the touch (the part that is iron), ambient temp is a 15.9
this thing as always ram warm, not sure if it has a bad component or is designed that way, you can imaging how hot it gets when the unit is closed
I know the APC units do not run close to this warm
the battery is cool to the touch, UPC is running on mains power
I was not sure if i needed a load on the system, so i hooked up my heated blanket, needless to say that made the cat happy

[petehall347]

Re: Transformer in UPS runs warm for no apparent reason

how much current is the battery drawing ?

[evilkitty]

Re: Transformer in UPS runs warm for no apparent reason

my clamp on meter shows 0.8A on the large red wire, 0.7A on the black wire (0.6 if i flip it around on the black wire)
may be worth noting this meter read 0.3A just sitting all by it self
*my other meter needs fuses (on order)

[momaka]

Re: Transformer in UPS runs warm for no apparent reason

30C doesn't seem that hot, even with 16C ambient. Your transformer will always draw a few Watts for itself, even when not loaded.

I have a pair of computer speakers whose transformer runs so hot that you can't even touch it (over 60C). This is regardless if the speakers are used or not, and with an average ambient temperature in my home at around 22-24C.

Most Class B -rated transformers are rated for up to 120 or 130C case temperature, if I remember correctly. So 30C really is nothing.

Nice cat, by the way! Always useful to have a pair of helping hands (or paws) around.

[ben7]

Re: Transformer in UPS runs warm for no apparent reason

That sounds normal to me. It's normal for a transformer to be warm even when unloaded, due to the "eddy current" losses in the iron core.

This is why environmentalists don't like iron-core transformer (mains frequency transformers) based power bricks, because the standby power draw is higher compared to that of a switch-mode power supply.

My guess is that the transformer is staying energized by the mains input in order to provide power to charge the battery.

-Ben

[budm]

Re: Transformer in UPS runs warm for no apparent reason

You have DC Clamp on amp meter?
"Running temp in open air is 27.5C to the touch (the part that is iron), ambient temp is a 15.9" Do mean that is the temperature during running on batteries mode WITH LOAD? That is only about 15 deg rise.

"my clamp on meter shows 0.8A on the large red wire, 0.7A on the black wire (0.6 if i flip it around on the black wire)" How much load is that on the batteries backup AC outlet? The get the power from 12V batteries and convert it to 120VAC, it will draws a lot more than 0.8A.

[evilkitty]

Re: Transformer in UPS runs warm for no apparent reason

Yep my camp on has AC and DC support, lowest setting is 40A, southwire 21050T
the AC load was about 65W (based on device setting and wattage label)
temp reads are when running on mains, heat is expected when running off battery and it makes far more than that

[evilkitty]

Re: Transformer in UPS runs warm for no apparent reason

30C doesn't seem that hot, even with 16C ambient. Your transformer will always draw a few Watts for itself, even when not loaded.

I have a pair of computer speakers whose transformer runs so hot that you can't even touch it (over 60C). This is regardless if the speakers are used or not, and with an average ambient temperature in my home at around 22-24C.

Most Class B -rated transformers are rated for up to 120 or 130C case temperature, if I remember correctly. So 30C really is nothing.

Nice cat, by the way! Always useful to have a pair of helping hands (or paws) around.

120C that will kill the caps!!!


this UPC also has a input voltage meter on it, it shows alot more fluctuation than any meter i have, anywhere from 105 to 126

[budm]

Re: Transformer in UPS runs warm for no apparent reason

Yep my camp on has AC and DC support, lowest setting is 40A, southwire 21050T
the AC load was about 65W (based on device setting and wattage label)
temp reads are when running on mains, heat is expected when running off battery and it makes far more than that

At 120VAC 65W load, if the batteries is 12V system then the current draw from batteries will be more than 5A. I cannot tell form the pictures as to how many 12V batteries are being used.
http://office.manualsonline.com/manu...000ub.html?p=2

[evilkitty]

Re: Transformer in UPS runs warm for no apparent reason

The Single battery is NOT UNDER LOAD, the unit is running on AC input, not DC output
in other words IF the battery needed charging the unit SHOULD be charging the battery not discharging it
i thought i made that clear in the original post, but hopefully this will clear that up

[budm]

Re: Transformer in UPS runs warm for no apparent reason

So the 65W load is NOT in UPS mode then, that is an interactive UPS so the load is basically connected directly to the incoming AC through the tap switching of that power transformer (also for charging the battery) to do simple AC out regulation when it is not in battery mode.
You need to use REL button to ZERO out your meter before making the current measurement.
The really verify the temp rise you will have to be in battery mode with full load which per spec, it will only run for about 3 minutes so the the temp rise will not be that fast to get to 120c (doubted that), the battery will run down by then.

[petehall347]

Re: Transformer in UPS runs warm for no apparent reason

on AC the battery is charging .
is there a min max setting for input voltage ?

[evilkitty]

Re: Transformer in UPS runs warm for no apparent reason

You mean a tolerance, sure
multimeter shows my mains at 116.5v variation of +0.1
battery is getting 13.5v

[evilkitty]

Re: Transformer in UPS runs warm for no apparent reason

With it in the case the air temp in the case is about 50C, this is just running off mains at with no AC load

[redwire]

Re: Transformer in UPS runs warm for no apparent reason

I find these low cost UPS just run really warm when doing nothing. Then the batteries don't last, due to the heat and high charging voltage for the warmer battery.

The transformer design is low cost with high flux density near saturation, so the core runs hot. Especially if your mains voltage is high >120VAC. It may have a shorted turn though.

The only other time I've seen these run hot and cook is if there is a shorted cell in the battery, it goes full tilt charging a 10V battery.


WINSSON ZHONGAING Transformer 62-1256 Tripp-Lite G1000UB UPS
Guy rips apart similar Winsson 62-1225 teardown

[Curious.George]

Re: Transformer in UPS runs warm for no apparent reason

With it in the case the air temp in the case is about 50C, this is just running off mains at with no AC load

Put a 10W light bulb in a similar case and I bet you find a similar rise in temperature!

Most consumer UPS's play the role of "toilet paper dispensers" in that toilet paper dispensers are generally cheaply made (to keep sell price low) and designed primarily to sell toilet paper (batteries, in the case of UPS's).

Amusingly, the commercial kit isn't that much better -- possibly because the IT departments have "battery budgets" and you can always play on their fear of a battery failing when it is most needed (so best err on the side of replacement!)

[momaka]

Re: Transformer in UPS runs warm for no apparent reason

Put a 10W light bulb in a similar case and I bet you find a similar rise in temperature!

Most consumer UPS's play the role of "toilet paper dispensers" in that toilet paper dispensers are generally cheaply made (to keep sell price low) and designed primarily to sell toilet paper (batteries, in the case of UPS's).

Exactly.
Although, I do want to explicitly mention that not all toilet paper dispensers are cheap. If you go to a "boutique"/home furniture store, you may find some really really expensive TP dispensers... like $40+ for a piece of stainless-steel rod with a funky shape.

This is why environmentalists don't like iron-core transformer (mains frequency transformers) based power bricks, because the standby power draw is higher compared to that of a switch-mode power supply.

For a well-designed transformer, it's not that high. But still likely to be more than 10 times that of a SMPS.

What I like about iron-core transformers is they don't introduce any EMI/RFI and distortion on the mains. Also, being inductive in nature, they may offset some of the poor capacitative PF from smaller switch-mode power adapters/chargers.

[Curious.George]

Re: Transformer in UPS runs warm for no apparent reason

Exactly.
Although, I do want to explicitly mention that not all toilet paper dispensers are cheap. If you go to a "boutique"/home furniture store, you may find some really really expensive TP dispensers... like $40+ for a piece of stainless-steel rod with a funky shape.

I designed a piece of medical (lab) equipment many years ago. Did my best to drive the product cost down to the lowest practical -- about $300 IIRC.

Customer "sold" the device for $6,000/each!

But, in practice, never collected any money for any of those sales -- instead, they were "toilet paper dispenser" designed to sell the "consumables" related to their use. By pricing it so high, THEIR customers thought they were getting a deal!